Method and apparatus for continuous injection molding

Abstract

Methods and apparatus for forming continuous lengths of material with non-uniform cross-sections are disclosed. In accordance with one aspect of the present invention, a method for forming a continuous length of material that is of a substantially non-constant cross-section includes providing the material to a single shaping wheel. The material is in a first state, and the single shaping wheel includes a template that is arranged to form a three-dimensional shape using the material. The method also includes shaping the material to form an extended strip from the material, as well as at least one three-dimensional shape in the extended strip. The extended strip and the three-dimensional shape being formed using substantially only the single shaping wheel. In one embodiment, the method includes cooling the extended strip by cooling the material from a molten state to a solid state.

What is claimed is:  
     
       1. A method for forming an extended strip having a thickness of greater than approximately one-eighth of an inch and a non-constant cross-section, the method comprising: 
       providing a molten molding material to a single rotating shaping wheel that includes a molding template having features thereon suitable for forming desired features in the molding material, wherein at least a portion of said molding template comprises a die that is distinct and separate from the single rotating shaping wheel, and wherein at least a portion of the molding template is oriented about the single rotating shaping wheel such that each molding template feature comprises a substantially constant cross-section along an axis extending from the center of the rotating shaping wheel through the feature, and wherein a substantial portion of the molding template features comprise at least one side profile that is exposed, thereby forming an extended strip having a thickness of greater than approximately one-eighth of an inch and a non-constant cross section comprising discrete shapes connected to a web via interconnects having widths smaller than the widths of their respective discrete shapes;  
       flattening the molten material within the shaping wheel as the shaping wheel rotates; and  
       removing the flattened extended strip having a thickness of greater than approximately one-eighth of an inch and a non-constant cross section from the shaping wheel.  
     
     
       2. A method as recited in  claim 1 , further comprising affirmatively cooling the flattened strip while the strip is on the shaping wheel, wherein the cooling transforms the molding material to a second state. 
     
     
       3. A method as recited in  claim 2 , further comprising after the removing step, passing the extended strip over a reshaping wheel arranged to substantially remove a curvature from the extended strip that is imparted by the shaping wheel thereby straightening the extended strip. 
     
     
       4. A method as recited in  claim 3  further comprising affirmatively cooling the straightened strip. 
     
     
       5. A method as recited in  claim 4  wherein the affirmative cooling operations each involve one of passing the strip through a trough of cooling water or spraying the strip with cooling water. 
     
     
       6. A method as recited in  claim 1  wherein the extended strip has a thickness of greater than approximately one-fourth of an inch. 
     
     
       7. A method as recited in  claim 1  further comprising the step of cutting the strip into lengths of greater than approximately six feet. 
     
     
       8. A method as recited in  claim 1  further comprising the step of deflashing the extended strip while it remains on the shaping wheel. 
     
     
       9. A method as recited in  claim 1  wherein the extended strip is formed substantially only from the molding material. 
     
     
       10. A method as recited in  claim 1 , further comprising after the removing step, passing the extended strip over a reshaping wheel arranged to substantially remove a curvature from the extended strip that is imparted by the shaping wheel thereby straightening the extended strip. 
     
     
       11. A method for forming an extended connector strip for holding together heat exchange tubes in plastic heat exchangers having a non-constant cross-section, the method comprising: 
       providing a molten molding material to a single rotating shaping wheel that includes a molding template having features thereon suitable for forming desired features in the molding material, wherein at least a portion of said molding template comprises a die that is distinct and separate from the single rotating shaping wheel;  
       flattening the molten material within the shaping wheel as the shaping wheel rotates; and  
       removing the flattened extended strip having a non-constant cross section from the shaping wheel.  
     
     
       12. A method as recited in  claim 11  wherein the extended strip has a thickness of greater than approximately one-eighth of an inch. 
     
     
       13. A method as recited in  claim 11  wherein the features formed in the extended strip are of a size greater than approximately one-eighth of an inch. 
     
     
       14. A method as recited in  claim 11 , further comprising the step of: 
       fitting said die onto said single rotating shaping wheel, wherein the die is removable from the single rotating shaping wheel.  
     
     
       15. A method as recited in  claim 11 , further comprising the step of: 
       shrink fitting said die onto said single rotating shaping wheel, wherein the die comprises a sheet of material welded into a hoop.  
     
     
       16. A method as recited in  claim 11  wherein a substantial portion of the molding template features comprise at least one side profile that is exposed. 
     
     
       17. A method as recited in  claim 11  wherein the molding template is oriented about the single rotating shaping wheel such that each molding template feature comprises a substantially constant cross-section along an axis extending from the center of the rotating shaping wheel through the feature. 
     
     
       18. A method for forming an extended connector strip for holding together heat exchange tubes in plastic heat exchangers having discrete shapes connected to a web via interconnects having widths smaller than the widths of their respective discrete shapes, the method comprising: 
       providing a molten molding material to a single rotating shaping wheel that includes a molding template having features thereon suitable for forming desired features in the molding material, thereby forming an extended strip having discrete shapes connected to a web via interconnects having widths smaller than the widths of their respective discrete shapes;  
       flattening the molten material within the shaping wheel as the shaping wheel rotates; and  
       removing the flattened extended strip having a non-constant cross section from the shaping wheel.  
     
     
       19. A method as recited in  claim 18  wherein the extended strip has a thickness of greater than approximately one-eighth of an inch. 
     
     
       20. A method as recited in  claim 18  wherein said discrete shapes are of a size greater than approximately one-eighth of an inch. 
     
     
       21. A method as recited in  claim 18 , further comprising the step of: 
       fitting a die onto said single rotating shaping wheel, wherein the die is distinct and separate from the single rotating shaping wheel and forms at least a portion of said molding template.  
     
     
       22. A method as recited in  claim 18 , further comprising the step of: 
       shrink fitting a die onto said single rotating shaping wheel, wherein the die comprises a sheet of material welded into a hoop.  
     
     
       23. A method as recited in  claim 18  wherein the molding template is oriented about the single rotating shaping wheel such that each molding template feature comprises a substantially constant cross-section along an axis extending from the center of the rotating shaping wheel through the feature. 
     
     
       24. A method as recited in  claim 18  wherein a substantial portion of the molding template features comprise at least one side profile that is exposed. 
     
     
       25. A method for forming an extended strip having a non-constant cross-section, the method comprising: 
       providing a molten molding material to a single rotating shaping wheel that includes a molding template having features thereon suitable for forming desired features in the molding material, wherein at least a portion of the molding template is oriented about the single rotating shaping wheel such that each molding template feature comprises a substantially constant cross-section along an axis extending from the center of the rotating shaping wheel through the feature, thereby forming an extended strip having a non-constant cross section;  
       flattening the molten material within the shaping wheel as the shaping wheel rotates; and  
       removing the flattened extended strip having a non-constant cross section from the shaping wheel.  
     
     
       26. A method as recited in  claim 25  wherein the extended strip has a thickness of greater than approximately one-eighth of an inch. 
     
     
       27. A method as recited in  claim 25  wherein a substantial portion of the molting template features comprise at least one side profile that is exposed. 
     
     
       28. A method for forming an extended connector strip for holding together heat exchange tubes in plastic heat exchangers having a non-constant cross-section, the method comprising: 
       providing a molten molding material to a single rotating shaping wheel that includes a molding template having features thereon suitable for forming desired features in the molding material, wherein a substantial portion of the molding template features comprise at least one side profile that is exposed, thereby forming a continuous strip having a non-constant cross section;  
       flattening the molten material within the shaping wheel as the shaping wheel rotates; and  
       removing the flattened extended strip having a non-constant cross section from the shaping wheel.  
     
     
       29. A method as recited in  claim 28  wherein the extended strip has a thickness of greater than approximately one-eighth of an inch. 
     
     
       30. A method for forming an extended connector strip for holding together heat exchange tubes in plastic heat exchangers having a thickness of greater than approximately one-eighth of an inch and a non-constant cross-section, the method comprising: 
       providing a molten molding material to a single rotating shaping wheel that includes a molding template having features thereon suitable for forming desired features in the molding material, thereby forming an extended strip having a thickness of greater than approximately one-eighth of an inch and a non-constant cross section;  
       flattening the molten material within the shaping wheel as the shaping wheel rotates; and  
       removing the flattened extended strip having a thickness of greater than approximately one-eighth of an inch and a non-constant cross section from the shaping wheel.  
     
     
       31. A method as recited in  claim 30 , further including the steps of: 
       affirmatively cooling the flattened strip while the strip is on the shaping wheel, wherein the cooling transforms the molding material to a second state;  
       deflashing the extended strip while it remains on the shaping wheel;  
       passing the removed strip over a reshaping wheel arranged to substantially remove a curvature from the strip that is imparted by the shaping wheel thereby straightening the continuous strip; and  
       cutting the strip into extended strips.